Power electronics is becoming more widely used in products belonging to the field of rotating electric machines, such as motors and alternators, with the aim of improving the output of the product per unit volume/weight and in response to market demand for improved efficiency. Moreover, recent years have witnessed accelerating movement toward reductions in the size of the products, in particular by employing electromechanically integrated structures.
More specifically, a conventional electric power steering apparatus is constructed by forming an inverter circuit for driving a motor from a plurality of molded modules and disposing the molded modules in a radial shape centering on a shaft on a film that is provided on an end portion of the motor and formed from a material exhibiting superior thermal conductivity, such as aluminum (see PTL 1, for example).
By configuring the electric power steering apparatus in this fashion, the inverter circuit, which is used to control a large current, can be formed efficiently in a small, compact size and disposed in the vicinity of the motor, and at the same time, heat can be dissipated and the modules can be fixed in a rational manner.
Further, an inverter module in which a module is formed in a trapezoidal shape and a plurality of modules are disposed close to each other in an overall annular shape, whereby an improvement in packaging efficiency is achieved, has been proposed (see PTL 2, for example).